Expandable luggage are well known. Many expandable luggage use a zipper expansion system comprising two frames, an expandable section of fabric attached between the two frames, and a zipper running along the perimeter of the luggage between the two frames. In other expandable luggage, the expandable section is located at the edge of the luggage without framing, in which case the expansion is soft. The zipper is closed to decrease the volume of the luggage by pulling together the two frames or expansion fabric and folding the expandable section into the interior of the luggage. The zipper is opened to expand the volume of the luggage by allowing the two frames to move apart and the expandable section to unfold.
The zipper expansion system has several disadvantages. One disadvantage is that the zipper expansion system does not enable a person to adjust the volume of the luggage to intermediate volumes between the zipped closed and zipped open configuration. This is because all of the fabric of the expandable section is loosened when the zipper is opened. Another disadvantage is that the expandable section does not provide a semi-rigid support to protect articles inside the luggage from external forces exerted on the luggage, such as other luggage placed on top of the luggage.
Another type of expansion system comprises two frames, plates attached to the frames, and a locking mechanism. The volume of the luggage is adjusted by sliding the plates attached to one of the frames along rails on the other frame. The locking mechanism is used to lock the plates into place at a desired volume. A disadvantage of this expansion system is that strong external forces exerted on the luggage, such as shock, can break and/or damage the locking mechanism.
Therefore, there is a need for an expansion system that enables a person to adjust the volume of luggage to intermediate volumes depending on the person's travel needs, provides semi-rigid support, and is not prone to break when strong external forces are exerted on luggage.